1. Field of the Invention
The invention concerns a feed station to feed a flat item which is fed individually or from a stack to a subsequent processing apparatus for the items. Such a flat item can be a thin mail piece such as postcards, “normal” mail goods of medium thickness (for example the standard letter in Germany) and thick mail pieces (for example the compact letter in Germany). The feed station has a controller that controls the feed so that a high throughput is achieved. The processor of the controller allows a selected mode of operation to be detected. Such a feed station can be used in connection with franking machines, addressing machines and other mail processing apparatuses.
2. Description of the Prior Art
Feeds of many different types are known in which the drive elements are mechanically coupled. Especially for short items, i.e. letters or mail pieces having a short format, the separation drive impresses a drive force on a subsequent item that follows a current item (i.e. letter or mail piece) very early so that items (i.e. letters or mail pieces) are separated (isolated) without large gaps there between or with insufficient gaps. Moreover, there is no possibility to vary these gaps within the feed.
A known separation device has two separation rollers and a transport device with one roller, with the rollers all permanently kinematically coupled with one another. A sluice of the separation device is formed by a gap between the second separation roller and by a number of fingers at the head of a rocker. The gap has dimensions that correspond to a width and a height of filled, commercially available letter envelopes. A stack of mail pieces is placed on the first separation roller. As soon as the first separation roller releases the lowermost mail piece of the stack via its rotation, a transport force is immediately impressed by the first separation roller on a respective second lowermost mail piece. This can lead to separation errors. In the most advantageous case, the advance of the second mail piece is stopped by the sluice of the separation device but represents a potential error source and unnecessary loading of the separation. Different formats likewise have an influence on the separation. Although the separation device can be adapted to other formats via a mechanical displacement or, respectively, adjustment, an automatic adaptation is not possible. Due to the lack of an additional sensor, no letter length measurement (and thus also no different control for different letter lengths) is possible. Additional disadvantages of the aforementioned separation device are that no gap measurement (and thus also no optimization of the gap), occurs, so that no error detection in the feed station is possible. The fixed kinematic coupling of the drive rollers does not allow a coordination of the separation velocity and/or the transport velocity, or a gap adjustment.
A franking system from Francotyp-Postalia GmbH has a feed station with a separation device and with a transport device, wherein—in the mail transport path—the feed station is arranged upstream in terms of mail flow of an Ultimail®-type franking machine. The separation device of the feed station has a transport belt in the pre-separation region. A drive drives the transport belt and the transport device, which are coupled with one another in terms of actuation. An additional drive acts on a separation roller. The sluice of the separation device is formed by a gap between the separation roller and by a number of fingers at the head of a rocker, which are arranged over the separation roller. It has been empirically established that the requirements for the reliability of the separation given a high throughput of flat items are satisfied with a high certainty only for a narrow spectrum (for example a defined type) of stacked mail goods. A sloped housing before the gap leads through a continuous tapering in the input region to the compression of the goods in the stack. Thick mail pieces cannot be separated from the stack if the gap through which a mail piece is sluiced has been set to be too narrow. However, if the gap has been set too wide, errors occur in the separation, in particular given a high throughput of flat items. The throughput likewise turns out to be less than possible due to large gaps between the successive mail pieces, in particular given short mail pieces (postcards, for example). The transport device has a closing device for open envelopes, which closing device is arranged between two transport rollers. An actuation device with a sealer button can bring the device into an operating position. In the operating position, an unsealed flap is raised from the envelope by a blade, moistened, and subsequently pressed onto the envelope by means of the second transport roller. As soon as the lowermost mail piece releases the first separation roller via rotation of the transport belt, a transport force is impressed by the first separation roller on a respective second mail piece. This can likewise lead to separation errors. The surface friction value of the transport belt must be very exactly matched to the mail piece surface so that a propulsive force that is too strong is not impressed on the respective second lowermost mail piece of the stack. The reliability of the separation would be increased if a propulsive force acts only on the mail piece that should be separated and supplied.
A separation device is known for flat articles is known from DE10127993A1, which separation device has a feed belt on driven deflection rollers and retention means, wherein in the latter a separation element is included which with the feed belt forms a sluice via which the separated flat articles are transported along the entire length. The feed belt is designed as a segmented belt that has a pull-in segment and a sliding segment. Upon placement of a mail piece or stack of mail pieces, a first and a second motor are automatically activated by a controller when a first sensor detects the placement. The stack is transported to the retention means of the separation means as soon as the first motor is activated. The stack is separated by the lowermost mail piece being removed, and the second motor is controlled accordingly by the controller. An encoder electrically connected with the controller serves for the detection of the positioned reached by the pull-in segment and (via the controller) secures the rotation speed constant of the second drive upon separation. The flat article can be pulled out from the separation device by the driving of the rollers of an ejection device via a third motor and can subsequently be ejected from the separation device, wherein the third motor is controlled by the controller. In spite of a significant cost in motors, sensors and mechanical components, the separation device does not allow a predetermined gap to be maintained between successive flat articles, in particular mail pieces with varying thickness and given the same format.